1. Field of the Invention
The invention relates to a seal device, more particularly to a seal device mounted between a rotary shaft and a stuffing box of a mixing machine. The invention also relates to a method for assembling a guide block in a gland of the seal device.
2. Description of the Related Art
A seal device is usually mounted in a stuffing box of a mixing machine so as to prevent leakage of fluid stirred in a stirring tank of the mixing machine due to high pressure in the stirring tank.
The seal device is usually classified into a single seal device and a dual seal device. No matter whether the seal device is single or dual, a gland of the seal device is provided with a fluid passage for permitting buffer/barrier fluid or flush fluid to flow therethrough. A guide member is provided in the fluid passage and is inclined so as to guide the fluid to flow smoothly in the fluid passage.
Referring to FIG. 1, a conventional seal device includes a gland 11 formed with an inlet 111 and an outlet 112 aligned with each other, and a guide member 12 annularly extending between the inlet 111 and the outlet 112 within a fluid passage 113. Since the guide member 12 occupies almost half of the fluid passage 113, the heat produced during operation cannot be removed effectively.
Referring to FIG. 2, another conventional seal device includes a gland 21 formed with an inlet 211 and an outlet 212, and a guide member 22 disposed between the inlet 211 and the outlet 212 within a fluid passage 213. The guide member 22 has a middle portion 221 connected to an inner peripheral surface of the gland 21, and two curved guiding portions 222 oppositely extending from the middle portion 221 so as to guide buffer/barrier fluid entering from the inlet 211 to flow through the fluid passage 213 and to exit from the outlet 212. However, turbulence and/or heat aggregation may occur in an area between the guiding portions 222, which in turn causes the guide member 22 to deform, especially when an external pressure is applied into the fluid passage 213.
Referring to FIG. 3, still another seal device disclosed in Taiwanese Utility Model No. M179519 includes a gland 32 formed with a positioning hole 322 communicated with a fluid passage 321, a guide block 31 disposed within the fluid passage 321, and a fixing member 33 inserted into the positioning hole 322 and engaging the guide block 31. The guide block 31 has two oppositely inclined end faces 312, and an inner curved surface 311 extending between the inclined end faces 312 so that the buffer/barrier fluid entering from two inlets 323 can be guided by the inclined end faces 312 of the guide block 31 so as to flow through the fluid passage 321 and exit from an outlet 325 to remove the heat produced due to the rotation of a rotary shaft 36.
Since the plane lines (S1) in which the inclined end faces 312 lie are not tangent to an outer peripheral face of a sleeve 35, the buffer/barrier fluid entering from the inlets 323 is sprayed onto an inner peripheral surface of the gland 32 prior to flowing smoothly in the fluid passage 321. In other words, the buffer/barrier fluid can not be effectively guided by the guide block 31 to flow smoothly in the fluid passage 321. Furthermore, since the fixing member 33 engages the guide block 31 merely at an end portion thereof, it can not be firmly positioned and engaged to the guide block 31. Therefore, the guide block 31 is liable to shake or the fixing member 33 is liable to break during operation of the rotary shaft 36, which in turn causes leakage of the buffer/barrier fluid.